British canal and river networks are in good shape, even in urban areas, according to an environmental study.

People taking part in the National Waterway Wildlife Survey made 4,000 sightings of various species.

They included more than 300 kingfishers - birds which are seen as a good indicator of healthy water systems.

British Waterways said there were good numbers of kingfishers in places such as central London, Manchester, Aylesbury, Coventry and Preston.

Kingfishers were the fourth most spotted bird species behind mallards, swans and herons.

Food chain

Also seen were water voles, otters and bats, and even some seals and a massive North American alligator snapping turtle.

British Waterways national ecology manager Mark Robinson said: "As well as being a strikingly beautiful bird, kingfishers are an important indicator of the general health of the waterway ecosystem as, like the big cats on the African plains, they are at the top of the waterway food chain.

"And good populations of kingfishers - even in urban areas - show the important role waterways have in greening our towns and cities by providing wildlife corridors which help sustain populations of a variety of both common and endangered species including bats, water voles and otters."

British Waterways is planning a number of improvements to kingfisher habitats at locations including Regent's Canal in London and the Grand Union Canal at Leighton Buzzard.

The organisation manages more than 2,200 miles of canals and rivers in England, Scotland and Wales.